Which one of the following to all methods of heat transfer require? a. A difference in thermal energy

b. A liquid or gaseous state

c. Direct physical contact

d. The movement of particles

The best solution for preventing harm to people and pets from severe hurricanes involves determining and warning residents about what

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride